MFH: r522326

net-p2p/monero-cli: fix build on non-x86

Architectures that don't have libunwind available should disable stack trace.

Otherwise, the following linking error is encountered:
/usr/local/bin/ld: src/common/libcommon.a(stack_trace.cpp.o): in function `tools::log_stack_trace(char const*)':
stack_trace.cpp:(.text+0x71c): undefined reference to `el::base::debug::StackTrace::generateNew()'
/usr/local/bin/ld: stack_trace.cpp:(.text+0x72c): undefined reference to `el::base::debug::operator<<(std::ostream&, el::base::debug::StackTrace const&)'
collect2: error: ld returned 1 exit status

PR: 242846
Approved by: vd (maintainer timeout)
Approved by: portmgr (fix build blanket)